U.S. patent application number 15/841870 was filed with the patent office on 2019-05-16 for channel-based positioning device, channel-based positioning system and channel-based positioning method.
The applicant listed for this patent is Industrial Technology Research Institute. Invention is credited to Pi-Chen Chiu, Ting-Wu Ho, Chia-Lung Liu.
Application Number | 20190146052 15/841870 |
Document ID | / |
Family ID | 60673843 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190146052 |
Kind Code |
A1 |
Chiu; Pi-Chen ; et
al. |
May 16, 2019 |
CHANNEL-BASED POSITIONING DEVICE, CHANNEL-BASED POSITIONING SYSTEM
AND CHANNEL-BASED POSITIONING METHOD
Abstract
The disclosure provides a channel-based positioning device, a
channel-based positioning system and a channel-based positioning
method. The channel-based positioning method includes: calculating
a plurality of angles of arrival (AoA), a plurality of angles of
departure (AoD) and a plurality of time of flight (ToF) of signals
according to a plurality of channel state information transmitted
from a terminal apparatus to a base station; determining a path
type of the signals according to the plurality of AoA, AoD and ToF
of the signals; and calculating a position information of the
terminal apparatus relative to the base station through a specific
algorithm.
Inventors: |
Chiu; Pi-Chen; (Hsinchu,
TW) ; Ho; Ting-Wu; (Hsinchu, TW) ; Liu;
Chia-Lung; (Hsinchu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Industrial Technology Research Institute |
Hsinchu |
|
TW |
|
|
Family ID: |
60673843 |
Appl. No.: |
15/841870 |
Filed: |
December 14, 2017 |
Current U.S.
Class: |
342/146 |
Current CPC
Class: |
H04B 7/024 20130101;
G01S 3/50 20130101; H04W 64/003 20130101; G01S 3/72 20130101; H04B
7/0413 20130101; G01S 5/0273 20130101; H04B 7/0626 20130101; H04W
4/023 20130101; G01S 3/60 20130101; G01S 5/06 20130101; G01S 5/0215
20130101; H04W 64/006 20130101 |
International
Class: |
G01S 3/72 20060101
G01S003/72; H04B 7/06 20060101 H04B007/06; G01S 3/60 20060101
G01S003/60; G01S 3/50 20060101 G01S003/50; H04W 64/00 20060101
H04W064/00; H04W 4/02 20060101 H04W004/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2017 |
TW |
106139175 |
Claims
1. A channel-based positioning device, comprising: a receiving
module configured for receiving a plurality of channel state
information (CSI) of a plurality of signals transmitted by a
terminal apparatus to a base station; a calculating module
configured for calculating a plurality of angles of departure
(AoD), a plurality of angles of arrival (AoA) and a plurality of
time of flight (ToF) of the plurality of signals of the terminal
apparatus relative to the base station based on the plurality of
CSI; a path type determining module configured for determining a
path type of the plurality of signals based on the plurality of
AoD, the plurality of AoA and the plurality of ToF; and a
positioning module configured for calculating position information
of the terminal apparatus relative to the base station based on the
path type of the plurality of signals.
2. The channel-based positioning device of claim 1, wherein the
terminal apparatus includes at least two terminal antennae, and the
base station includes at least two base station antennae.
3. The channel-based positioning device of claim 2, wherein the
plurality of AoA are calculated based on phase differences between
signals transmitted respectively from one of the at least two
terminal antennae to any two of the at least two base station
antennae.
4. The channel-based positioning device of claim 2, wherein the
plurality of AoD are calculated based on phase differences between
signals transmitted respectively from any two of the at least two
terminal antennae to one of the at least two base station
antennae.
5. The channel-based positioning device of claim 2, wherein the
plurality of ToF are calculated based on phase differences between
sub-carriers of a signal transmitted from one of the at least two
terminal antennae to one of the at least two base station
antennae.
6. The channel-based positioning device of claim 2, wherein when a
difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold and a
difference between the ToF of the signals from the two terminal
antennae reaches a second threshold, the path type determining
module determines that the path type of the signals belong to a
single-signal reflected path type, and the positioning module
calculates the position information using an angle-side-angle
triangle congruence theorem.
7. The channel-based positioning device of claim 2, wherein when a
difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae has not reached a first
threshold and the AoD of the two terminal antennae has a greater
one of different standard deviations, the path type determining
module determines that the path type of the signals belong to a
double-signal same-direction reflected path type, and the
positioning module calculates the position information using a
side-side-side triangle congruence theorem.
8. The channel-based positioning device of claim 2, wherein when a
difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold, a
difference between the ToF of the signals from the two terminal
antennae has not reached a second threshold and the AoD of the two
terminal antennae are dividable into two groups, the path type
determining module determines that the path type of the signals
belong to a double-signal opposite-direction reflected path type,
and the positioning module calculates the position information
using a side-side-side triangle congruence theorem.
9. The channel-based positioning device of claim 2, wherein when a
difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold, a
difference between the ToF of the signals from the two terminal
antennae has not reached a second threshold and the AoD of the two
terminal antennae are not dividable into two groups, or when the
difference between the AoA or the AoD of the signals from the two
terminal antennae has not reached the first threshold and the AoD
of the two terminal antennae has a less one of different standard
deviations, the path type determining module determines that the
path type of the signals belong to a double-signal direct path
type, and the positioning module calculates the position
information using a right angle-hypotenuse-side triangle congruence
theorem.
10. A channel-based positioning system, comprising: a base station;
a terminal apparatus configured for transmitting a plurality of
signals to the base station for the base station to obtain a
plurality of channel state information (CSI); and a positioning
device, including: a receiving module configured for receiving the
plurality of CSI; a calculating module configured for calculating a
plurality of angles of departure (AoD), a plurality of angles of
arrival (AoA) and a plurality of time of flight (ToF) of the
plurality of signals of the terminal apparatus relative to the base
station based on the plurality of CSI; a path type determining
module configured for determining a path type of the plurality of
signals based on the plurality of AoD, the plurality of AoA and the
plurality of ToF; and a positioning module configured for
calculating position information of the terminal apparatus relative
to the base station based on the path type of the plurality of
signals.
11. The channel-based positioning system of claim 10, wherein the
terminal apparatus includes at least two terminal antennae, and the
base station includes at least two base station antennae.
12. The channel-based positioning system of claim 11, wherein the
plurality of AoA are calculated based on phase differences between
signals transmitted respectively from one of the at least two
terminal antennae to any two of the at least two base station
antennae.
13. The channel-based positioning system of claim 11, wherein the
plurality of AoD are calculated based on phase differences between
signals transmitted respectively from any two of the at least two
terminal antennae to one of the at least two base station
antennae.
14. The channel-based positioning system of claim 11, wherein the
plurality of ToF are calculated based on phase differences between
sub-carriers of a signal transmitted from one of the at least two
terminal antennae to one of the at least two base station
antennae.
15. The channel-based positioning system of claim 11, wherein when
a difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold and a
difference between the ToF of the signals from the two terminal
antennae reaches a second threshold, the path type determining
module determines that the path type of the signals belong to a
single-signal reflected path type, and the positioning module
calculates the position information using an angle-side-angle
triangle congruence theorem.
16. The channel-based positioning system of claim 11, wherein when
a difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae has not reached a first
threshold and the AoD of the two terminal antennae has a greater
one of different standard deviations, the path type determining
module determines that the path type of the signals belong to a
double-signal same-direction reflected path type, and the
positioning module calculates the position information using a
side-side-side triangle congruence theorem.
17. The channel-based positioning system of claim 11, wherein when
a difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold, a
difference between the ToF of the signals from the two terminal
antennae has not reached a second threshold and the AoD of the two
terminal antennae are dividable into two groups, the path type
determining module determines that the path type of the signals
belong to a double-signal opposite-direction reflected path type,
and the positioning module calculates the position information
using a side-side-side triangle congruence theorem.
18. The channel-based positioning system of claim 11, wherein when
a difference between the AoA or the AoD of signals from any two of
the at least two terminal antennae reaches a first threshold, a
difference between the ToF of the signals from the two terminal
antennae has not reached a second threshold and the AoD of the two
terminal antennae are not dividable into two groups, or when the
difference between the AoA or the AoD of the signals from the two
terminal antennae has not reached the first threshold and the AoD
of the two terminal antennae has a less one of different standard
deviations, the path type determining module determines that the
path type of the signals belong to a double-signal direct path
type, and the positioning module calculates the position
information using a right angle-hypotenuse-side triangle congruence
theorem.
19. A channel-based positioning method, comprising: obtaining a
plurality of channel state information (CSI) of a plurality of
signals transmitted by a terminal apparatus to a base station;
calculating a plurality of angles of departure (AoD), a plurality
of angles of arrival (AoA) and a plurality of time of flight (ToF)
of the plurality of signals of the terminal apparatus relative to
the base station based on the plurality of CSI; determining a path
type of the plurality of signals based on the plurality of AoD, the
plurality of AoA and the plurality of ToF; and calculating position
information of the terminal apparatus relative to the base station
based on the path type of the plurality of signals.
20. The channel-based positioning method of claim 19, wherein the
terminal apparatus includes at least two terminal antennae, and the
base station includes at least two base station antennae.
21. The channel-based positioning method of claim 20, wherein the
plurality of AoA are calculated based on phase differences between
signals transmitted respectively from one of the at least two
terminal antennae to any two of the at least two base station
antennae.
22. The channel-based positioning method of claim 20, wherein the
plurality of AoD are calculated based on phase differences between
signals transmitted respectively from any two of the at least two
terminal antennae to one of the at least two base station
antennae.
23. The channel-based positioning method of claim 20, wherein the
plurality of ToF are calculated based on phase differences between
sub-carriers of a signal transmitted from one of the at least two
terminal antennae to one of the at least two base station
antennae.
24. The channel-based positioning method of claim 20, further
comprising when a difference between the AoA or the AoD of signals
from any two of the at least two terminal antennae reaches a first
threshold and a difference between the ToF of the signals from the
two terminal antennae reaches a second threshold, determining that
the path type of the signals belong to a single-signal reflected
path type, and calculating the position information using an
angle-side-angle triangle congruence theorem.
25. The channel-based positioning method of claim 20, further
comprising when a difference between the AoA or the AoD of signals
from any two of the at least two terminal antennae has not reached
a first threshold and the AoD of the two terminal antennae has a
greater one of different standard deviations, determining that the
path type of the signals belong to a double-signal same-direction
reflected path type, and calculating the position information using
a side-side-side triangle congruence theorem.
26. The channel-based positioning method of claim 20, further
comprising when a difference between the AoA or the AoD of signals
from any two of the at least two terminal antennae reaches a first
threshold, a difference between the ToF of the signals from the two
terminal antennae has not reached a second threshold and the AoD of
the two terminal antennae are dividable into two groups,
determining that the path type of the signals belong to a
double-signal opposite-direction reflected path type, and
calculating the position information using a side-side-side
triangle congruence theorem.
27. The channel-based positioning method of claim 20, further
comprising when a difference between the AoA or the AoD of signals
from any two of the at least two terminal antennae reaches a first
threshold, a difference between the ToF of the signals from the two
terminal antennae has not reached a second threshold and the AoD of
the two terminal antennae are not dividable into two groups, or
when the difference between the AoA or the AoD of the signals from
the two terminal antennae has not reached the first threshold and
the AoD of the two terminal antennae has a less one of different
standard deviations, determining that the path type of the signals
belong to a double-signal direct path type, and calculating the
position information using a right angle-hypotenuse-side triangle
congruence theorem.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present disclosure is based on, and claims priority
from, Taiwan Application Number 106139175, filed Nov. 13, 2017, the
disclosure of which is hereby incorporated by reference herein in
its entirety.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to positioning devices,
positioning systems and positioning methods, and, more
particularly, to a channel-based positioning device, a
channel-based positioning system and a channel-based positioning
method that require only a terminal apparatus and a single base
station.
2. Description of Related Art
[0003] Global Positioning System (GPS) provides accurate,
convenient and fast positioning. With the popularity of smart
phones, GPS has more applications. However, due to the limitation
of its technical principle, the positioning accuracy of this
positioning technology in the indoor environment is often not
satisfactory. Therefore, a Wi-Fi indoor positioning method has been
proposed.
[0004] This traditional Wi-Fi indoor positioning method involves
calculating the distance by analyzing parameters of the signal in
the propagation process, such as the received signal strength (RSS)
and so on. However, in this indoor positioning method, differences
of the received signal strengths under different circumstances will
increase errors in positioning. Thus, a Channel State Information
(CSI) positioning method was developed. This CSI positioning method
uses parameters such as Angle of Arrival (AoA) and Time of Flight
(ToF) of the signals. However, the existing CSI positioning method
must use at least three base stations to calculate the position of
the terminal apparatus to reduce the positioning error and improve
the accuracy. If only one base station is used, positioning errors
may be too large to satisfy indoor positioning requirements, and
signal strengths may be need to be re-measured when there is a
change in the indoor environment.
SUMMARY OF THE DISCLOSURE
[0005] A channel-based positioning device is provided, which may
include: a receiving module configured for receiving a plurality of
channel state information (CSI) of a plurality of signals
transmitted by a terminal apparatus to a base station; a
calculating module configured for calculating a plurality of angles
of departure (AoD), a plurality of angles of arrival (AoA) and a
plurality of time of flight (ToF) of the plurality of signals of
the terminal apparatus relative to the base station based on the
plurality of CSI; a path type determining module configured for
determining a path type of the plurality of signals based on the
plurality of AoD, the plurality of AoA and the plurality of ToF;
and a positioning module configured for calculating position
information of the terminal apparatus relative to the base station
based on the path type of the plurality of signals.
[0006] The present disclosure also provides a channel-based
positioning system, which may include: a base station; a terminal
apparatus configured for transmitting a plurality of signals to the
base station for the base station to obtain a plurality of channel
state information (CSI); and a positioning device, including: a
receiving module configured for receiving the plurality of CSI; a
calculating module configured for calculating a plurality of angles
of departure (AoD), a plurality of angles of arrival (AoA) and a
plurality of time of flight (ToF) of the plurality of signals of
the terminal apparatus relative to the base station based on the
plurality of CSI; a path type determining module configured for
determining a path type of the plurality of signals based on the
plurality of AoD, the plurality of AoA and the plurality of ToF;
and a positioning module configured for calculating position
information of the terminal apparatus relative to the base station
based on the path type of the plurality of signals.
[0007] The present disclosure further provides a channel-based
positioning method, which may include: obtaining a plurality of
channel state information (CSI) of a plurality of signals
transmitted by a terminal apparatus to a base station; calculating
a plurality of angles of departure (AoD), a plurality of angles of
arrival (AoA) and a plurality of time of flight (ToF) of the
plurality of signals of the terminal apparatus relative to the base
station based on the plurality of CSI; determining a path type of
the plurality of signals based on the plurality of AoD, the
plurality of AoA and the plurality of ToF; and calculating position
information of the terminal apparatus relative to the base station
based on the path type of the plurality of signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic diagram depicting the framework of a
channel-based positioning system in accordance with the present
disclosure;
[0009] FIG. 2 is a schematic diagram depicting a terminal apparatus
transmitting signals to a base station in the positioning system in
accordance with the present disclosure;
[0010] FIG. 3A is a schematic diagram depicting a positioning
device in the positioning system calculating angle of arrival (AoA)
of signals incident on the base station in accordance with the
present disclosure;
[0011] FIG. 3B is a schematic diagram depicting the positioning
device in the positioning system calculating angle of departure
(AoD) of signals transmitted from the terminal apparatus in
accordance with the present disclosure;
[0012] FIG. 4A is a schematic diagram depicting the positioning
device in the positioning system determining signals to be of a
double-signal direct path type in accordance with the present
disclosure;
[0013] FIG. 4B is a schematic diagram depicting the positioning
device in the positioning system determining signals to be of a
single-signal reflected path type in accordance with the present
disclosure;
[0014] FIG. 4C is a schematic diagram depicting the positioning
device in the positioning system determining signals to be of a
double-signal same-direction reflected path type in accordance with
the present disclosure;
[0015] FIG. 4D is a schematic diagram depicting the positioning
device in the positioning system determining signals to be of a
double-signal opposite-direction reflected path type in accordance
with the present disclosure;
[0016] FIG. 5 is a graph depicting a plurality of AoD of signals
and their distances drawn in coordinates for determining the
signals to be of the double-signal opposite-direction reflected
path type by the positioning device in the positioning system of
the present disclosure;
[0017] FIG. 6A is a graph depicting a plurality of AoD of signals
and their distances drawn in coordinates for determining the
signals to be of the double-signal same-direction reflected path
type by the positioning device in the positioning system of the
present disclosure;
[0018] FIG. 6B is a graph depicting a plurality of AoD of signals
and their distances drawn in coordinates for determining the
signals to be of the double-signal direct path type by the
positioning device in the positioning system of the present
disclosure;
[0019] FIG. 7 is a flowchart illustrating a positioning method in
accordance with the present disclosure;
[0020] FIG. 8 is a flowchart illustrating determining a path type
of the signals in the positioning method in accordance with the
present disclosure; and
[0021] FIG. 9 is a schematic diagram illustrating a comparison
between the positioning methods of present disclosure and the prior
art.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] The present disclosure is described by the following
specific embodiments. Those with ordinary skills in the arts can
readily understand other advantages and functions of the present
disclosure after reading the disclosure of this specification. The
present disclosure may also be practiced or applied with other
different implementations. Based on different contexts and
applications, the various details in this specification can be
modified and changed without departing from the spirit of the
present disclosure.
[0023] Referring to FIG. 1, a schematic diagram depicting a
channel-based positioning system 1 and a positioning device 30
thereof in accordance with the present disclosure is shown. The
positioning system 1 according to the present disclosure includes a
base station 10, a terminal apparatus 20 and the positioning device
30. The positioning device 30 includes a receiving module 31, a
calculating module 32, a path type determining module 33 and a
positioning module 34.
[0024] In an embodiment, the base station 10 can be a Wi-Fi access
point (AP) or a base station (BS), or a base station erected by a
telecommunication company, and the terminal apparatus 20 can be a
smart phone, a tablet and the like. In another embodiment, the
positioning device 30 can be a location based service (LBS)
server.
[0025] The terminal apparatus 20 is used for transmitting a
plurality of signals 35 to the base station 10, such that the base
station 10 obtains a plurality of channel state information (CSI).
Refer to FIG. 2 at the same time. In an embodiment, the terminal
apparatus 20 includes at least two terminal antennae 21 and 22, and
the base station 10 includes at least two base station antennae 11,
12 and 13. The plurality of signals 35 transmitted by the terminal
apparatus 20 to the base station 10 may be uplink CSI. Since the
terminal apparatus 20 includes at least two terminal antennae 21
and 22 and the base station 10 includes at least two base station
antennae 11, 12 and 13, uplink CSI between different terminal
antennae and different base station antennae may be different. The
base station 10 may simultaneously receive uplink CSI uploaded by a
plurality of terminal apparatuses 20. Thus, the base station 10
identifies the uplink CSI between different terminal apparatuses 20
and their different antennae based on identifications (ID) and
antenna ports of the terminal apparatuses 20.
[0026] As shown in FIG. 2, in an embodiment if the terminal
apparatus 20 has two terminal antennae 21 and 22 and the base
station 10 includes three base station antennae 11, 12 and 13, the
CSI transmitted by the terminal antennae 21 and 22 to the base
station antennae 11, 12 and 13 can be represented in a CSI matrix
S.sub.n, m, wherein n indicates the n.sup.th antenna of the
terminal apparatus 20, and m indicates the m.sup.th antenna of the
base station 10. Therefore, the CSI matrix transmitted by a
terminal antenna to a base station antenna can be, for example,
represented as:
S.sub.1,2=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30]
[0027] In an embodiment, a CSI may also include a Timestamp of each
packet and a MAC address of the terminal apparatus 20, and each
signal may include 30 sub-carriers.
[0028] The plurality of CSI obtained by the base station 10 can
then be transmitted to the positioning device 30, such that the
receiving module 31 of the positioning device 30 receives the
plurality of CSI. In this embodiment, the receiving module 31 is
hardware, such as a network interface, a connection port and the
like, and the present disclosure does not so limit the type of
connection between the receiving module 31 and the base station
10.
[0029] In an embodiment, the calculating module 32, the path type
determining module 33 and the positioning module 34 in the
positioning device 30 are software or firmware implemented by a
microprocessor in the positioning device 30. The software can be
stored in a storage unit (e.g., a hard disk, a USB, a flash memory
or etc.) in the positioning device 30 to be processed by the
microprocessor. The firmware can be burnt on a read-only memory to
be processed by the microprocessor, but the present disclosure is
not limited as such.
[0030] Referring to FIG. 2, the calculating module 32 is used for
calculating a plurality of angles of departure (AoD), a plurality
of angles of arrival (AoA) and a plurality of time of flight (ToF)
of signals of the terminal apparatus 20 relative to the base
station 10 based on the plurality of CSI, for example, an AoD
.phi.1 of a signal 351 when transmitted from the terminal antenna
21; an AoD .phi.2 of a signal 352 when transmitted from the
terminal antenna 22; an AoA .theta.1 of the signal 351 when
arriving at the base station antenna 12; an AoA .theta.2 of the
signal 352 when arriving at the base station antenna 12; and the
like.
[0031] In an embodiment, as shown in FIG. 2, the signal 351 travels
in a straight line path without being reflected by an obstruction
40 and arrives at the base station antenna 12 directly, while the
signal 352 travels in a reflected path in which it is reflected by
the obstruction 40 once and then received by the base station
antenna 12. The present disclosure does not limit the type of paths
taken by the signals 351 and 352. The signals 351 and 352 may both
travel in straight line paths or both travel in reflected paths, or
one may travel in a straight line path, while the other travels in
a reflected path and vice versa. Embodiments about the types of
paths will be described in more details later.
[0032] In an embodiment, referring to FIG. 3A, a schematic diagram
illustrating the calculation of AoA of signals incident on the base
station is shown. Assuming the CSI matrix of a signal 351' is
S.sub.1,1=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30], and the CSI
matrix of a signal 352' is S.sub.1,2=[CSI.sub.1 CSI.sub.2 . . .
CSI.sub.30]. The signals 351' and 352' are both transmitted by the
same terminal antenna on the terminal apparatus 20 and received by
different base station antennae 11 and 12 on the base station 10,
respectively. The AoA .theta. can be calculated based on the
equation below:
.DELTA. phase 2 .pi. = d sin .theta. .lamda. , ##EQU00001##
[0033] wherein .DELTA.phase is the phase difference between the CSI
matrix S.sub.1,1=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30] of the
signal 351' received by the base station antenna 11 and the CSI
matrix S.sub.1,2=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30] of the
signal 352' received by the base station antenna 12 (for example,
the phase difference between each CSI.sub.1, i.e., the phase
difference between the base station antennae); d is the distance
between the base station antenna 11 and base station antenna 12,
.lamda. is the wavelength (e.g., the wavelength of a 2.4 GHz wave
is about 125 mm, the wavelength of a 5.0 GHz wave is about 60 mm);
and 2.pi. for expressing in radians (360 degrees).
[0034] In an embodiment, referring to FIG. 3B, a schematic diagram
illustrating the calculation of AoD of signals transmitted by the
terminal apparatus is shown. Assuming the CSI matrix of the signal
351 is S.sub.1,1=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30] and the CSI
matrix of the signal 352 is S.sub.2,1=[CSI.sub.1 CSI.sub.2 . . .
CSI.sub.30]. The signals 351 and 352 are transmitted by different
terminal antennas 21 and 22, respectively, on the terminal
apparatus 20 and received by the same base station antenna on the
base station 10. The AoD .phi. can be calculated based on the
equation below:
.DELTA. phase 2 .pi. = d sin .PHI. .lamda. , ##EQU00002##
[0035] wherein .DELTA.phase is the phase difference between the CSI
matrix S.sub.1,1=[CSI.sub.1 CSI.sub.2 . . . CSI.sub.30] of the
signal 351 and the CSI matrix S.sub.2,1=[CSI.sub.1 CSI.sub.2 . . .
CSI.sub.30] of the signal 352 transmitted by the terminal apparatus
20 (for example, the phase difference between each CSI.sub.1, i.e.,
the phase difference between the terminal antennae); d is the
distance between the terminal antennae 21 and 22, .lamda. is the
wavelength (e.g., the wavelength of a 2.4 GHz wave is about 125 mm,
the wavelength of a 5.0 GHz wave is about 60 mm); and 2.pi. for
expressing in radians (360 degrees).
[0036] In an embodiment, the ToF can be calculated based on the
phase difference between sub-carriers of a signal transmitted from
one of the terminal antennae to one of the at least two base
station antennae. For example, the CSI matrix of the signal 351
transmitted by the terminal apparatus 20 to the base station
antenna 12 of the base station 10 is S.sub.1,1=[CSI.sub.1 CSI.sub.2
. . . CSI.sub.30], it includes 30 sub-carriers. The ToF of the
signal 351 can be calculated according to the equation below:
n .times. ( c f 1 - c f 2 ) c f 2 = .DELTA. phase 2 .pi.
##EQU00003##
[0037] Substitute
T 1 = 1 f 1 ##EQU00004##
into the above equation to get:
n.times.T.sub.1.times.(f.sub.2-f.sub.1).times.2.pi.=.DELTA.phase,
[0038] wherein .DELTA.phase is the phase difference between the
sub-carriers in the above S.sub.1,1=[CSI.sub.1 CSI.sub.2 . . .
CSI.sub.30] (e.g., the phase difference between CSI.sub.1 and
CSI.sub.2); c is the speed of light; f.sub.1 and f.sub.2 are the
frequencies of different sub-carriers(e.g., the frequencies of
CSI.sub.1 and CSI.sub.2); 2.pi. for expressing in radians (360
degrees); n is the number of sub-carrier; and T is the ToF.
[0039] Once the plurality of the AoD, the AoA and the ToF of the
signals are determined, the path type determining module 33 then
determines the types of paths of the signals 351 and 352 based on
the plurality of the AoD, the AoA and the ToF. FIGS. 4A to 4D
illustrate four embodiments in which the positioning device in the
positioning system determines the types of paths of signals in
accordance with the present disclosure. The determining method is
described in FIG. 8. In the descriptions below, the signals 351 and
352 are used for illustration purpose only, and the present
disclosure is not limited to just two signals.
[0040] First, as shown in step S21, it is determined whether the
difference between the AoA .theta.1 and .theta.2 of the signals 351
and 352 or the AoD .phi.1 and .phi.2 of the signals 351 and 352
(e.g., |.theta.1-.theta.2| or |.phi.1-.phi.2|) has reached a first
threshold. If it has reached the first threshold, step S22 is
executed to further determine if the difference between the ToF of
the signals 351 and 352 has reached a second threshold. If it has
reached the second threshold, the path type determining module 33
determines that the path type of the signals is a single-signal
reflected path type, as shown in FIG. 4B, the signal 351 travels in
a straight line path without being reflected by the obstruction 40
and arrives at the base station antenna 12 directly, while the
signal 352 travels in a reflected path in which it is reflected by
the obstruction 40 (reflection point 401) once and then received by
the base station antenna 12.
[0041] In an embodiment, the first threshold is a range of angles,
such as 40 to 80 degrees, 50 to 70 degrees etc. The first threshold
may also be a specific angle, such as 60 degrees, but the present
disclosure is not limited as such. In addition, the difference
between the ToF of the signals 351 and 352 means that the longer
one of the ToF of the signals is greater than the shorter one of
the ToF of the signals by a specific multiple, and this specific
multiple is the second threshold. In an embodiment, this specific
multiple (i.e., the second threshold) can be one or two, preferably
1.5. Alternatively, the second threshold can be a range of
multiples, for example, between one and two multiples, and the
present disclosure is not limited as such.
[0042] If in step S21, the difference between the AoA .theta.1 and
.theta.2 of the signals 351 and 352 or the AoD .phi.1 and .phi.2 of
the signals 351 and 352 (e.g., |.theta.1-.theta.2| or
|.phi.1-.phi.2|) has not reached the first threshold, then proceed
to step S23 to determine whether the standard deviation between the
AoD .phi.1 and .phi.2 of the signals 351 and 352 is large. If so,
then the path type determining module 33 may determine that the
path type of the signals 351 and 352 belong to a double-signal
same-direction reflected path type, as shown in FIG. 4C, the
signals 351 and 352 are reflected by the same obstruction 40
(reflection points 401 and 402) once and then received by the base
station 10. If not, then the path type determining module 33
determines the path type of the signals 351 and 352 belong to a
double-signal direct path type, as shown in FIG. 4A, the signals
351 and 352 directly arrive at the base station 10 without
intervening obstructions. Herein, the method for determining the
standard deviation is described with respect to FIGS. 6A and 6B,
wherein the AoD and the distances (or ToF) are drawn in graphs of
coordinates. It can be seen in FIGS. 6A and 6B, a packet cluster 53
is more loosely packed than a packet cluster 54, i.e., the packet
cluster 54 is more concentrated than the packet cluster 53.
Therefore, the packet cluster 54 (see FIG. 6B) indicates the
double-signal direct path type, while the packet cluster 53 (see
FIG. 6A) indicates the double-signal same-direction reflected
path.
[0043] If in step S22, the second threshold is not reached, then
proceed to step S24 to further determine whether the AoD .phi.1 and
.phi.2 can be divided into two groups. If so, then the path type
determining module 33 determines that the path type of the signals
351 and 352 belong to a double-signal opposite-direction reflected
path type, as shown in FIG. 4D, the signal 351 is reflected once by
an obstruction 40' (reflection point 401') before arriving at the
base station antenna 12, and the signal 352 is reflected once by
the obstruction 40 (reflection point 401) before arriving at the
base station antenna 12. In other words, this type of path entails
that the signals 351 and 352 being reflected by different
obstructions 40 and 40'. The above step of determining whether the
AoD can be divided into two groups can be seen in FIG. 5, wherein
the AoD and the distances (or ToF) are drawn in a graph of
coordinates, and if two distinct packet clusters 51 and 52 are
shown, then it is determined the AoD of the signals can be divided
into two groups, otherwise the opposite is true.
[0044] In step S24, since the AoD .phi.1 and .phi.2 cannot be
divided into two groups, then the path type determining module 33
determines that the path type of the signals 351 and 352 is also
the double-signal direct path type as described before with respect
to FIG. 4A.
[0045] Once the path type determining module 33 has determined the
path type of the signals, the positioning module 34 then calculates
a position information of the terminal apparatus 20 relative to the
base station 10 using a specific algorithm depending on the path
type of the signals. Details of the algorithms corresponding to
different path types are described below.
[0046] Returning to FIG. 4A, the signals 351 and 352 belong to the
double-signal direct path type. As an example, the terminal
antennae 21 and 22 transmit signals to the base station antenna 12,
the vertical distance z between the base station 10 and the
terminal apparatus 20 is the position information to be calculated
by the positioning module 34. At this time, the connections between
the terminal antennae 21 and 22 and the base station antenna 12 can
be regarded as a congruent triangle (RHS). Since the AoA .theta.1
and the ToF of the signal 351 are known, then the distance d1 from
the terminal antenna 21 to the base station antenna 12 can be
calculated based on the ToF of the signal 351. The distance z can
be obtained by the equation below and the position information can
be further obtained:
z=d.sub.1 cos(.theta.1).
[0047] Referring now to FIG. 4B, the signals 351 and 352 belong to
the single-signal reflected path type. If the distance between the
terminal antennae 21 and 22 of the terminal apparatus 20 is
ignored, then the terminal 20, the base station 10 and the
reflection point 401 of the obstruction 40 form a congruent
triangle with two angles and one included side (ASA), wherein .phi.
is sum of .phi.1 and .phi.2, .theta. is the difference between
.theta.2 and .theta.1, and the positioning module 34 can calculate
the distance z from the ToF of the signal 351 as the position
information of the terminal apparatus 20 relative to the base
station 10.
[0048] Referring to FIG. 4C, the signals 351 and 352 belong to the
double-signal same-direction reflected path type. If the distance
between the terminal antennae 21 and 22 of the terminal apparatus
20 is ignored, the terminal apparatus 20, the base station 10 and
the reflection points 401 and 402 of the obstruction 40 form two
three-side congruent triangles (SSS) respectively. Since the AoD
.phi.1, the AoD .theta.1 and the ToF of the signal 351 are known,
the distance d1 of the signal 351 can first be calculated. Assuming
the distance of the signal 351 between the base station 10 and the
reflection point 402 is x, then the distance of the signal 351
between the reflection point 402 and the terminal apparatus 20
would be d1-x, and the vertical distance between the base station
10 and the reflection point 402 would be x sin(.pi./2-.theta.1),
and the vertical distance between the reflection point 402 and the
terminal apparatus 20 would be (d1-x)sin(.pi./2-.phi.1); similarly,
the total distance of the signal 352 is d2, assuming the distance
of the signal 352 between the base station 10 and the reflection
point 401 is y, then the distance of the signal 352 between the
reflection point 401 and the terminal apparatus 20 would be d2-y,
and the vertical distance between the base station 10 and the
reflection point 401 would be y sin(.pi./2-.theta.2), and the
vertical distance between the reflection point 401 and the terminal
apparatus 20 would be (d2-y)sin(.pi./2.phi.2). Therefore, using
cosine theorem, the distance z between the terminal apparatus 20
and the base station 10 can be solved with the following
equation:
z.sup.2=x.sup.2+(d.sub.1-x).sup.2+2x(d.sub.1-x)cos(.pi.-.theta..sub.1-.p-
hi..sub.1)=y.sup.2+(d.sub.2-y).sup.2+2y(d.sub.2-y)cos(.pi.-.theta..sub.2-.-
phi..sub.2)
[0049] Referring to FIG. 4D, the signals 351 and 352 belong to the
double-signal opposite-direction reflected path type. If the
distance between the terminal antennae 21 and 22 of the terminal
apparatus 20 is ignored, then the terminal apparatus 20, the base
station 10 and the reflection point 401 of the obstruction 40 and
the reflection point 401' of the obstruction 40' form two
three-side congruent triangles (SSS) respectively. Since the AoD
.phi.1, the AoD .theta.1 and the ToF of the signal 351 are known,
the distance d1 of the signal 351 can first be calculated. Assuming
the distance of the signal 351 between the base station 10 and the
reflection point 401' is x, then the distance of the signal 351
between the reflection point 401' and the terminal apparatus 20
would be d1-x, and the horizontal distance between the base station
10 and the reflection point 401 would be x cos(.pi./2-.theta.1),
and the horizontal distance between the reflection point 401' and
the terminal apparatus 20 would be (d1-x)cos(.pi./2-.phi.1);
similarly, the total distance of the signal 352 is d2, assuming the
distance of the signal 352 between the base station 10 and the
reflection point 401 is y, then the distance of the signal 352
between the reflection point 401 and the terminal apparatus 20
would be d2-y, and the horizontal distance between the base station
10 and the reflection point 401 would be y cos(.pi./2-.theta.2),
and the horizontal distance between the reflection point 401 and
the terminal apparatus 20 would be (d2-y)cos(.pi./2-.phi.2).
Therefore, using cosine theorem, the distance z between the two
reflection points 401 and 401' can be solved with the following
equation:
z.sup.2=x.sup.2+y.sup.2+2xy
cos(.theta..sub.1+.theta..sub.2)=(d.sub.1-x).sup.2+(d.sub.2-y).sup.2+2(d.-
sub.1-x)(d.sub.2-y)cos(.phi..sub.1+.phi..sub.2)
[0050] After the position information of the terminal apparatus 20
relative to the base station 10 is calculated by the positioning
module 34 of the positioning device 30, the positioning device 30
returns this position information back to the terminal apparatus 20
for further use by the terminal apparatus 20. The way in which the
position information is represented may be relative coordinates of
the terminal apparatus 20 with respect to the base station 10, or
absolute coordinates; the present disclosure is not limited as
such.
[0051] In an embodiment, the positioning device 30 may not
determine the position information after just a single calculation,
rather a plurality of calculations are made before the average of
the obtained calculations is used as the position information.
[0052] Referring to FIG. 7, a channel-based positioning method is
further disclosed. In step S11, a plurality of channel state
information (CSI) of a plurality of signals transmitted by a
terminal apparatus to a base station are obtained. Then, proceed to
step S12. In step S12, a plurality of angles of departure (AoD),
angles of arrival (AoA) and time of flight (ToF) of the plurality
of signals are calculated based on the plurality of CSI
information. Then, proceed to step S13. In step S13, the type of
path of the plurality of signals is determined based on the
plurality of AoD, AoA and ToF. Then, proceed to step S14. In step
S14, a position information of the terminal apparatus relative to
the base station is calculated through a specific algorithm
depending on the type of path of the plurality of signals.
[0053] In an embodiment, the step of determining the type of path
of the plurality of signals in step S13 can further include step
S21 to S24 described with respect to FIG. 8.
[0054] The technical details of above steps S11 to S14 and steps
S21 to S24 of the positioning method of the present disclosure are
substantially the same as the above descriptions with respect to
the positioning system 1, and will not be repeated.
[0055] Referring further to FIG. 9, a schematic diagram depicting a
comparison between the positioning methods of the present
disclosure and the prior art. A curve 61 indicates measurement
results obtained using the technique of the present disclosure,
while curve 62 indicates measurement results obtained using the
technique of the prior art. As can be seen in FIG. 9, the
positioning error of the present disclosure (curve 61) is
significantly smaller than that of the prior art (curve 62).
Therefore, the present disclosure is indeed capable of providing
more accurate positioning results compared to the prior art.
[0056] With the positioning device, the positioning system and the
positioning method according to the present disclosure, positioning
information of a terminal apparatus can be obtained with just a
single base station by first calculating the AoD, the AoA and the
ToF of the signals transmitted by different terminal antennae of
the terminal apparatus to the base station, determining the path
type of the signals, and then determining the positioning
information of the terminal apparatus relative to the base station
by a specific algorithm depending on the path types. Therefore, the
positioning technique according to the present disclosure is based
on a terminal apparatus with at least two antennae. Compared to the
prior art in which three base stations are needed for positioning,
the present disclosure using just a single base station is able to
provide smaller positioning errors and higher accuracy, satisfying
the requirements for indoor positioning. It also eliminates the
need to re-measure the signal strengths due to a change in the
indoor environment as encountered in the prior art.
[0057] The above embodiments are only used to illustrate the
principles of the present disclosure, and should not be construed
as to limit the present disclosure in any way. The above
embodiments can be modified by those with ordinary skill in the art
without departing from the scope of the present disclosure as
defined in the following appended claims.
* * * * *